Special Pic

Support - Thank You!

UHN Research Publicity

The hippocampus (in red) processes and stores information about where objects are in space, known as spatial memory.

Computational Neuroscience: The Relationship between Individual Neurons and Population Network Activities

Announced on Jul 18, 2012 (UHN Research News on intranet) and part of UHN online publication - Net Results EXPRESS (NRx) July 2012.

The hippocampus is the region of the brain responsible for processing
a number of important functions, including memory formation and
storage. Hippocampus activity is controlled in part by inhibitory cells
and the networks they comprise. The individual inhibitory cells fire at
high frequencies but collectively produce activities at significantly
slower rhythms—termed slow population activities (SPAs). While the
underlying mechanisms that help to coordinate this network are poorly
understood, TWRI Senior Scientist Dr. Frances Skinner
and her former doctoral student, Ernest Ho, have recently shed new
light on the coordination of neuron activity in the hippocampus.

Drs. Ho, Skinner and their collaborators used a multifaceted approach
consisting of computer simulations, mathematical analyses, experimental
analyses and validation to show that low frequency SPAs are due to both
the existence of particular properties of inhibitory cells and network
interactions. Specifically, when excitatory and inhibitory network
interactions are balanced, the network can transition from one state to
another, allowing SPAs to emerge as part of the inhibitory response.
This switching ability occurs if the fast-spiking inhibitory cells have a
steep change in firing rate activity and are supported by the network
interactions in this regime during hippocampus activation.

Using interneuron recordings from mice and rat models, a plot of
frequency versus current produced results that were consistent with the
model predictions. “This is the first study to have uncovered the
precise conditions in a physiological context that promote network
multistability,” explains Dr. Skinner. “The fundamental understanding
achieved will contribute to hippocampal function and dysfunction
understanding from network perspectives, as well as give insight into
underlying mechanisms in other brain regions.”